Generally, in an electrophotographic recording type image forming apparatus, a photoconductive drum is irradiated with laser beam to form an electrostatic latent image. The photoconductive drum forms a toner image with the toner supplied from a developing device, and transfers the toner image to a paper to form an image. In the developing device, when the toner in the developing device is insufficient, toner is replenished from a toner replenishing port of the developing device. Further, at time of shipment, setting, maintenance and the like, the serviceman fills the two-component developing agent including toner and carrier through a developing agent filling port into the empty developing agent housing section.
Further, when the two-component developing agent is used repeatedly, the carrier of the two-component developing agent is gradually deteriorated and the developing capability is reduced, thus the developing agent including the deteriorated carrier is exchanged by the serviceman. Conventionally, when inputting the developing agent to the developing device, the following work is needed, that is, a process unit is taken out from the main body, the lid of the developing device is opened to input the developing agent, and then the process unit is installed in the main body again. Further, for facilitating the work, there is a mechanism in which the developing agent is automatically input to the developing device from a cartridge by sealing the developing agent in the cartridge and setting the cartridge in the main body of the image forming apparatus.
However, in the above-mentioned mechanism, in addition to the toner cartridge, a developing agent cartridge needs to be installed in the main body, and thus, there is a problem that additional space is required. Further, in the example disclosed in Japanese Unexamined Patent Application Publication No. Hei 8-185033, that the developing agent container and the toner container are set to one container is disclosed.
The example disclosed in Japanese Unexamined Patent Application Publication No. Hei 8-185033 is only applicable to the apparatus having a mechanism in which the whole toner container rotates. Further, at time of shipment, setting, and maintenance, the toner concentration is adjusted to be a given ratio when replenishing the developing agent; however, since the toner container is not sealed, there is a possibility that some toner is replenished. Thus, the toner concentration (TC) within the two-component developing agent is changed, which affects the gradation reproducibility, and results in an image failure.